In order to achieve objectives for identifying and managing content and providing related information when distributing content such as the image, video and voice, there is a method using the digital watermark technology for imperceptibly embedding another information into the content. Generally, a digital watermark detection object image is subjected to geometric transformation so that it includes geometric distortion. Therefore, a digital watermark technology that has tolerance to such geometric transformation is needed.
As a conventional technology for detecting and correcting the geometric transformation, there is a technology described in the patent document 1. In the technology described in the patent document 1, a pattern for correcting geometric transformation is embedded separately from an embedding image so that the geometric transformation is detected by using the pattern.
[patent document 1] Japanese Laid Open Patent Application No. 11-355547